CIH Hazards & Exposures 5

Question 1

Which dose-response model assumes that any level of exposure to a carcinogen carries some finite risk — i.e., there is no threshold below which risk is zero?

Accepted Answer

Linear non-threshold (LNT) model

Answer

The linear non-threshold model assumes carcinogenic risk increases linearly from zero dose, with no safe threshold, and is commonly applied to genotoxic carcinogens.

Question 2

A laboratory worker is accidentally exposed to a nerve agent simulant that inhibits acetylcholinesterase. Which physiologic effect would be expected?

Accepted Answer

Excessive secretions, miosis, bradycardia, and muscle fasciculations (cholinergic crisis)

Answer

Acetylcholinesterase inhibition prevents breakdown of acetylcholine, causing overstimulation of muscarinic and nicotinic receptors resulting in a cholinergic toxidrome.

Question 3

An IH is monitoring workers in a spray painting booth that uses an HVOC coating. Air sampling results show exposures are below PELs, but the IDLH for the solvent blend is 500 ppm and the highest measured concentration is 420 ppm. What action is most appropriate?

Accepted Answer

Treat the atmosphere as IDLH and require supplied-air respirators; concentrations >10% of IDLH require SCBA or SAR

Answer

OSHA requires supplied-air respirators when concentrations are at or above 10% of the IDLH value (here 50 ppm), and when approaching IDLH, escape-only SCBAs are mandatory.

Question 4

Which occupational disease is caused by inhalation of cotton, flax, or hemp dust and is characterized by chest tightness that is worst on Monday mornings?

Accepted Answer

Byssinosis

Answer

Byssinosis ('brown lung') is caused by organic cotton dust and classically presents with Monday morning chest tightness that improves as the week progresses.

Question 5

A heat stress evaluation using the Wet Bulb Globe Temperature (WBGT) index weighs three measurements. Which component carries the highest weighting factor outdoors?

Accepted Answer

Natural wet bulb temperature (NWB)

Answer

The outdoor WBGT formula is 0.7 NWB + 0.2 GT + 0.1 DB, assigning the greatest weight (70%) to the natural wet bulb to reflect evaporative cooling's dominance.

CIH - Certified Industrial Hygienist Exam Practice Test

CIH - Certified Industrial Hygienist Exam Practice Test

CIH Hazards & Exposures 5